Question

我的班级有这一行：

private static readonly ILog log = LogManager.GetLogger(typeof(Prim));

当我进行单元测试时，我无法将moq记录器注入此接口，因此我可以计算日志调用。

有办法做到这一点吗？ Log4net建议记录器使用静态只读模式。处理它的最佳方法是什么？

Answer 1

虽然log4net推荐使用此模式，但没有什么可以阻止您在类外部实例化记录器并注入它。大多数IoC可以配置为注入一个相同的实例。这样，对于您的单元测试，您可以注入模拟。

我建议使用LogManager.GetLogger的包装器，它总是返回一个和每个类型相同的记录器实例：

namespace StackOverflowExample.Moq
{
    public interface ILogCreator
    {
        ILog GetTypeLogger<T>() where T : class;
    }

    public class LogCreator : ILogCreator
    {
        private static readonly IDictionary<Type, ILog> loggers = new Dictionary<Type, ILog>();
        private static readonly object lockObject;

        public ILog GetTypeLogger<T>() where T : class
        {
            var loggerType = typeof (T);
            if (loggers.ContainsKey(loggerType))
            {
                return loggers[typeof (T)];
            }

            lock (lockObject)
            {
                if (loggers.ContainsKey(loggerType))
                {
                    return loggers[typeof(T)];
                }
                var logger = LogManager.GetLogger(loggerType);
                loggers[loggerType] = logger;
                return logger;
            }
        }
    }

    public class ClassWithLogger
    {
        private readonly ILog logger;
        public ClassWithLogger(ILogCreator logCreator)
        {
            logger = logCreator.GetTypeLogger<ClassWithLogger>();
        }

        public void DoSomething()
        {
            logger.Debug("called");
        }
    }

    [TestFixture]
    public class Log4Net
    {
        [Test]
        public void DoSomething_should_write_in_debug_logger()
        {
            //arrange
            var logger = new Mock<ILog>();
            var loggerCreator = Mock.Of<ILogCreator>(
                c =>
                c.GetTypeLogger<ClassWithLogger>() == logger.Object);

            var sut = new ClassWithLogger(loggerCreator);

            //act
            sut.DoSomething();

            //assert
            logger.Verify(l=>l.Debug("called"), Times.Once());
        }
    }
}

Answer 2

您可以使用MemoryAppender代替模拟记录器。通过这种方法，您可以配置log4net以收集内存中的日志事件，并通过GetEvents()进行验证。

我找到了这些有用的例子：

这是第一个：

[SetUp]
public void SetUp()
{
    this.memoryAppender = new MemoryAppender();
    BasicConfigurator.Configure(this.memoryAppender);

    ...
}

[Test]
public void TestSomething()
{
    ...

    // Assert
    Assert.IsFalse(
        this.memoryAppender.GetEvents().Any(le => le.Level == Level.Error),
        "Did not expect any error messages in the logs");
}

更详细：

public static class Log4NetTestHelper
{
    public static string[] RecordLog(Action action)
    {
        if (!LogManager.GetRepository().Configured)
            BasicConfigurator.Configure();
        var logMessages = new List<string>();
        var root = ((log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository()).Root;
        var attachable = root as IAppenderAttachable;

        var appender = new MemoryAppender();
        if (attachable != null)
            attachable.AddAppender(appender);

        try
        {           
            action();
        }
        finally
        {
            var loggingEvents = appender.GetEvents();
            foreach (var loggingEvent in loggingEvents)
            {
                var stringWriter = new StringWriter();
                loggingEvent.WriteRenderedMessage(stringWriter);
                logMessages.Add(string.Format("{0} - {1} | {2}", loggingEvent.Level.DisplayName, loggingEvent.LoggerName, stringWriter.ToString()));
            }
            if (attachable != null)
                attachable.RemoveAppender(appender);
        }

        return logMessages.ToArray();
    }
}

C＃Static Readonly log4net logger，在Unit Test中改变记录器的方法有哪些？

2 个答案: